#include <json/reader.h>
#include <json/value.h>
#include <utility>
#include <cstdio>
#include <cassert>
#include <cstring>
#include <iostream>
#include <stdexcept>

#if _MSC_VER >= 1400 // VC++ 8.0
#pragma warning( disable : 4996 )   // disable warning about strdup being deprecated.
#endif

namespace Json
{

// Implementation of class Features
// ////////////////////////////////

    Features::Features()
        : allowComments_( true )
        , strictRoot_( false )
    {
    }


    Features
    Features::all()
    {
        return Features();
    }


    Features
    Features::strictMode()
    {
        Features features;
        features.allowComments_ = false;
        features.strictRoot_ = true;
        return features;
    }

// Implementation of class Reader
// ////////////////////////////////


    static inline bool
    in( Reader::Char c, Reader::Char c1, Reader::Char c2, Reader::Char c3, Reader::Char c4 )
    {
        return c == c1  ||  c == c2  ||  c == c3  ||  c == c4;
    }

    static inline bool
    in( Reader::Char c, Reader::Char c1, Reader::Char c2, Reader::Char c3, Reader::Char c4, Reader::Char c5 )
    {
        return c == c1  ||  c == c2  ||  c == c3  ||  c == c4  ||  c == c5;
    }


    static bool
    containsNewLine( Reader::Location begin,
                     Reader::Location end )
    {
        for ( ; begin < end; ++begin )
            if ( *begin == '\n'  ||  *begin == '\r' )
                return true;

        return false;
    }

    static std::string codePointToUTF8( unsigned int cp )
    {
        std::string result;

        // based on description from http://en.wikipedia.org/wiki/UTF-8

        if ( cp <= 0x7f )
        {
            result.resize( 1 );
            result[0] = static_cast<char>( cp );
        }
        else if ( cp <= 0x7FF )
        {
            result.resize( 2 );
            result[1] = static_cast<char>( 0x80 | ( 0x3f & cp ) );
            result[0] = static_cast<char>( 0xC0 | ( 0x1f & ( cp >> 6 ) ) );
        }
        else if ( cp <= 0xFFFF )
        {
            result.resize( 3 );
            result[2] = static_cast<char>( 0x80 | ( 0x3f & cp ) );
            result[1] = 0x80 | static_cast<char>( ( 0x3f & ( cp >> 6 ) ) );
            result[0] = 0xE0 | static_cast<char>( ( 0xf & ( cp >> 12 ) ) );
        }
        else if ( cp <= 0x10FFFF )
        {
            result.resize( 4 );
            result[3] = static_cast<char>( 0x80 | ( 0x3f & cp ) );
            result[2] = static_cast<char>( 0x80 | ( 0x3f & ( cp >> 6 ) ) );
            result[1] = static_cast<char>( 0x80 | ( 0x3f & ( cp >> 12 ) ) );
            result[0] = static_cast<char>( 0xF0 | ( 0x7 & ( cp >> 18 ) ) );
        }

        return result;
    }


// Class Reader
// //////////////////////////////////////////////////////////////////

    Reader::Reader()
        : features_( Features::all() )
    {
    }


    Reader::Reader( const Features &features )
        : features_( features )
    {
    }


    bool
    Reader::parse( const std::string &document,
                   Value &root,
                   bool collectComments )
    {
        document_ = document;
        const char *begin = document_.c_str();
        const char *end = begin + document_.length();
        return parse( begin, end, root, collectComments );
    }


    bool
    Reader::parse( std::istream& sin,
                   Value &root,
                   bool collectComments )
    {
        //std::istream_iterator<char> begin(sin);
        //std::istream_iterator<char> end;
        // Those would allow streamed input from a file, if parse() were a
        // template function.

        // Since std::string is reference-counted, this at least does not
        // create an extra copy.
        std::string doc;
        std::getline( sin, doc, ( char )EOF );
        return parse( doc, root, collectComments );
    }

    bool
    Reader::parse( const char *beginDoc, const char *endDoc,
                   Value &root,
                   bool collectComments )
    {
        if ( !features_.allowComments_ )
        {
            collectComments = false;
        }

        begin_ = beginDoc;
        end_ = endDoc;
        collectComments_ = collectComments;
        current_ = begin_;
        lastValueEnd_ = 0;
        lastValue_ = 0;
        commentsBefore_ = "";
        errors_.clear();

        while ( !nodes_.empty() )
            nodes_.pop();

        nodes_.push( &root );

        bool successful = readValue();
        Token token;
        skipCommentTokens( token );

        if ( collectComments_  &&  !commentsBefore_.empty() )
            root.setComment( commentsBefore_, commentAfter );

        if ( features_.strictRoot_ )
        {
            if ( !root.isArray()  &&  !root.isObject() )
            {
                // Set error location to start of doc, ideally should be first token found in doc
                token.type_ = tokenError;
                token.start_ = beginDoc;
                token.end_ = endDoc;
                addError( "A valid JSON document must be either an array or an object value.",
                          token );
                return false;
            }
        }

        return successful;
    }


    bool
    Reader::readValue()
    {
        Token token;
        skipCommentTokens( token );
        bool successful = true;

        if ( collectComments_  &&  !commentsBefore_.empty() )
        {
            currentValue().setComment( commentsBefore_, commentBefore );
            commentsBefore_ = "";
        }


        switch ( token.type_ )
        {
        case tokenObjectBegin:
            successful = readObject( token );
            break;

        case tokenArrayBegin:
            successful = readArray( token );
            break;

        case tokenNumber:
            successful = decodeNumber( token );
            break;

        case tokenString:
            successful = decodeString( token );
            break;

        case tokenTrue:
            currentValue() = true;
            break;

        case tokenFalse:
            currentValue() = false;
            break;

        case tokenNull:
            currentValue() = Value();
            break;

        default:
            return addError( "Syntax error: value, object or array expected.", token );
        }

        if ( collectComments_ )
        {
            lastValueEnd_ = current_;
            lastValue_ = &currentValue();
        }

        return successful;
    }


    void
    Reader::skipCommentTokens( Token &token )
    {
        if ( features_.allowComments_ )
        {
            do
            {
                readToken( token );
            }
            while ( token.type_ == tokenComment );
        }
        else
        {
            readToken( token );
        }
    }


    bool
    Reader::expectToken( TokenType type, Token &token, const char *message )
    {
        readToken( token );

        if ( token.type_ != type )
            return addError( message, token );

        return true;
    }


    bool
    Reader::readToken( Token &token )
    {
        skipSpaces();
        token.start_ = current_;
        Char c = getNextChar();
        bool ok = true;

        switch ( c )
        {
        case '{':
            token.type_ = tokenObjectBegin;
            break;

        case '}':
            token.type_ = tokenObjectEnd;
            break;

        case '[':
            token.type_ = tokenArrayBegin;
            break;

        case ']':
            token.type_ = tokenArrayEnd;
            break;

        case '"':
            token.type_ = tokenString;
            ok = readString();
            break;

        case '/':
            token.type_ = tokenComment;
            ok = readComment();
            break;

        case '0':
        case '1':
        case '2':
        case '3':
        case '4':
        case '5':
        case '6':
        case '7':
        case '8':
        case '9':
        case '-':
            token.type_ = tokenNumber;
            readNumber();
            break;

        case 't':
            token.type_ = tokenTrue;
            ok = match( "rue", 3 );
            break;

        case 'f':
            token.type_ = tokenFalse;
            ok = match( "alse", 4 );
            break;

        case 'n':
            token.type_ = tokenNull;
            ok = match( "ull", 3 );
            break;

        case ',':
            token.type_ = tokenArraySeparator;
            break;

        case ':':
            token.type_ = tokenMemberSeparator;
            break;

        case 0:
            token.type_ = tokenEndOfStream;
            break;

        default:
            ok = false;
            break;
        }

        if ( !ok )
            token.type_ = tokenError;

        token.end_ = current_;
        return true;
    }


    void
    Reader::skipSpaces()
    {
        while ( current_ != end_ )
        {
            Char c = *current_;

            if ( c == ' '  ||  c == '\t'  ||  c == '\r'  ||  c == '\n' )
                ++current_;
            else
                break;
        }
    }


    bool
    Reader::match( Location pattern,
                   int patternLength )
    {
        if ( end_ - current_ < patternLength )
            return false;

        int index = patternLength;

        while ( index-- )
            if ( current_[index] != pattern[index] )
                return false;

        current_ += patternLength;
        return true;
    }


    bool
    Reader::readComment()
    {
        Location commentBegin = current_ - 1;
        Char c = getNextChar();
        bool successful = false;

        if ( c == '*' )
            successful = readCStyleComment();
        else if ( c == '/' )
            successful = readCppStyleComment();

        if ( !successful )
            return false;

        if ( collectComments_ )
        {
            CommentPlacement placement = commentBefore;

            if ( lastValueEnd_  &&  !containsNewLine( lastValueEnd_, commentBegin ) )
            {
                if ( c != '*'  ||  !containsNewLine( commentBegin, current_ ) )
                    placement = commentAfterOnSameLine;
            }

            addComment( commentBegin, current_, placement );
        }

        return true;
    }


    void
    Reader::addComment( Location begin,
                        Location end,
                        CommentPlacement placement )
    {
        assert( collectComments_ );

        if ( placement == commentAfterOnSameLine )
        {
            assert( lastValue_ != 0 );
            lastValue_->setComment( std::string( begin, end ), placement );
        }
        else
        {
            if ( !commentsBefore_.empty() )
                commentsBefore_ += "\n";

            commentsBefore_ += std::string( begin, end );
        }
    }


    bool
    Reader::readCStyleComment()
    {
        while ( current_ != end_ )
        {
            Char c = getNextChar();

            if ( c == '*'  &&  *current_ == '/' )
                break;
        }

        return getNextChar() == '/';
    }


    bool
    Reader::readCppStyleComment()
    {
        while ( current_ != end_ )
        {
            Char c = getNextChar();

            if ( c == '\r'  ||  c == '\n' )
                break;
        }

        return true;
    }


    void
    Reader::readNumber()
    {
        while ( current_ != end_ )
        {
            if ( !( *current_ >= '0'  &&  *current_ <= '9' )  &&
                    !in( *current_, '.', 'e', 'E', '+', '-' ) )
                break;

            ++current_;
        }
    }

    bool
    Reader::readString()
    {
        Char c = 0;

        while ( current_ != end_ )
        {
            c = getNextChar();

            if ( c == '\\' )
                getNextChar();
            else if ( c == '"' )
                break;
        }

        return c == '"';
    }


    bool
    Reader::readObject( Token &tokenStart )
    {
        Token tokenName;
        std::string name;
        currentValue() = Value( objectValue );

        while ( readToken( tokenName ) )
        {
            bool initialTokenOk = true;

            while ( tokenName.type_ == tokenComment  &&  initialTokenOk )
                initialTokenOk = readToken( tokenName );

            if ( !initialTokenOk )
                break;

            if ( tokenName.type_ == tokenObjectEnd  &&  name.empty() )  // empty object
                return true;

            if ( tokenName.type_ != tokenString )
                break;

            name = "";

            if ( !decodeString( tokenName, name ) )
                return recoverFromError( tokenObjectEnd );

            Token colon;

            if ( !readToken( colon ) ||  colon.type_ != tokenMemberSeparator )
            {
                return addErrorAndRecover( "Missing ':' after object member name",
                                           colon,
                                           tokenObjectEnd );
            }

            Value &value = currentValue()[ name ];
            nodes_.push( &value );
            bool ok = readValue();
            nodes_.pop();

            if ( !ok ) // error already set
                return recoverFromError( tokenObjectEnd );

            Token comma;

            if ( !readToken( comma )
                    || ( comma.type_ != tokenObjectEnd  &&
                         comma.type_ != tokenArraySeparator &&
                         comma.type_ != tokenComment ) )
            {
                return addErrorAndRecover( "Missing ',' or '}' in object declaration",
                                           comma,
                                           tokenObjectEnd );
            }

            bool finalizeTokenOk = true;

            while ( comma.type_ == tokenComment &&
                    finalizeTokenOk )
                finalizeTokenOk = readToken( comma );

            if ( comma.type_ == tokenObjectEnd )
                return true;
        }

        return addErrorAndRecover( "Missing '}' or object member name",
                                   tokenName,
                                   tokenObjectEnd );
    }


    bool
    Reader::readArray( Token &tokenStart )
    {
        currentValue() = Value( arrayValue );
        skipSpaces();

        if ( *current_ == ']' ) // empty array
        {
            Token endArray;
            readToken( endArray );
            return true;
        }

        int index = 0;

        while ( true )
        {
            Value &value = currentValue()[ index++ ];
            nodes_.push( &value );
            bool ok = readValue();
            nodes_.pop();

            if ( !ok ) // error already set
                return recoverFromError( tokenArrayEnd );

            Token token;
            // Accept Comment after last item in the array.
            ok = readToken( token );

            while ( token.type_ == tokenComment  &&  ok )
            {
                ok = readToken( token );
            }

            bool badTokenType = ( token.type_ == tokenArraySeparator  &&
                                  token.type_ == tokenArrayEnd );

            if ( !ok  ||  badTokenType )
            {
                return addErrorAndRecover( "Missing ',' or ']' in array declaration",
                                           token,
                                           tokenArrayEnd );
            }

            if ( token.type_ == tokenArrayEnd )
                break;
        }

        return true;
    }


    bool
    Reader::decodeNumber( Token &token )
    {
        bool isDouble = false;

        for ( Location inspect = token.start_; inspect != token.end_; ++inspect )
        {
            isDouble = isDouble
                       ||  in( *inspect, '.', 'e', 'E', '+' )
                       || ( *inspect == '-'  &&  inspect != token.start_ );
        }

        if ( isDouble )
            return decodeDouble( token );

        Location current = token.start_;
        bool isNegative = *current == '-';

        if ( isNegative )
            ++current;

        Value::UInt threshold = ( isNegative ? Value::UInt( -Value::minInt )
                                  : Value::maxUInt ) / 10;
        Value::UInt value = 0;

        while ( current < token.end_ )
        {
            Char c = *current++;

            if ( c < '0'  ||  c > '9' )
                return addError( "'" + std::string( token.start_, token.end_ ) + "' is not a number.", token );

            if ( value >= threshold )
                return decodeDouble( token );

            value = value * 10 + Value::UInt( c - '0' );
        }

        if ( isNegative )
            currentValue() = -Value::Int( value );
        else if ( value <= Value::UInt( Value::maxInt ) )
            currentValue() = Value::Int( value );
        else
            currentValue() = value;

        return true;
    }


    bool
    Reader::decodeDouble( Token &token )
    {
        double value = 0;
        const int bufferSize = 32;
        int count;
        int length = int( token.end_ - token.start_ );

        if ( length <= bufferSize )
        {
            Char buffer[bufferSize];
            memcpy( buffer, token.start_, length );
            buffer[length] = 0;
            count = sscanf( buffer, "%lf", &value );
        }
        else
        {
            std::string buffer( token.start_, token.end_ );
            count = sscanf( buffer.c_str(), "%lf", &value );
        }

        if ( count != 1 )
            return addError( "'" + std::string( token.start_, token.end_ ) + "' is not a number.", token );

        currentValue() = value;
        return true;
    }


    bool
    Reader::decodeString( Token &token )
    {
        std::string decoded;

        if ( !decodeString( token, decoded ) )
            return false;

        currentValue() = decoded;
        return true;
    }


    bool
    Reader::decodeString( Token &token, std::string &decoded )
    {
        decoded.reserve( token.end_ - token.start_ - 2 );
        Location current = token.start_ + 1; // skip '"'
        Location end = token.end_ - 1;      // do not include '"'

        while ( current != end )
        {
            Char c = *current++;

            if ( c == '"' )
                break;
            else if ( c == '\\' )
            {
                if ( current == end )
                    return addError( "Empty escape sequence in string", token, current );

                Char escape = *current++;

                switch ( escape )
                {
                case '"':
                    decoded += '"';
                    break;

                case '/':
                    decoded += '/';
                    break;

                case '\\':
                    decoded += '\\';
                    break;

                case 'b':
                    decoded += '\b';
                    break;

                case 'f':
                    decoded += '\f';
                    break;

                case 'n':
                    decoded += '\n';
                    break;

                case 'r':
                    decoded += '\r';
                    break;

                case 't':
                    decoded += '\t';
                    break;

                case 'u':
                {
                    unsigned int unicode;

                    if ( !decodeUnicodeCodePoint( token, current, end, unicode ) )
                        return false;

                    decoded += codePointToUTF8( unicode );
                }
                break;

                default:
                    return addError( "Bad escape sequence in string", token, current );
                }
            }
            else
            {
                decoded += c;
            }
        }

        return true;
    }

    bool
    Reader::decodeUnicodeCodePoint( Token &token,
                                    Location &current,
                                    Location end,
                                    unsigned int &unicode )
    {

        if ( !decodeUnicodeEscapeSequence( token, current, end, unicode ) )
            return false;

        if ( unicode >= 0xD800 && unicode <= 0xDBFF )
        {
            // surrogate pairs
            if ( end - current < 6 )
                return addError( "additional six characters expected to parse unicode surrogate pair.", token, current );

            unsigned int surrogatePair;

            if ( *( current++ ) == '\\' && *( current++ ) == 'u' )
            {
                if ( decodeUnicodeEscapeSequence( token, current, end, surrogatePair ) )
                {
                    unicode = 0x10000 + ( ( unicode & 0x3FF ) << 10 ) + ( surrogatePair & 0x3FF );
                }
                else
                    return false;
            }
            else
                return addError( "expecting another \\u token to begin the second half of a unicode surrogate pair", token, current );
        }

        return true;
    }

    bool
    Reader::decodeUnicodeEscapeSequence( Token &token,
                                         Location &current,
                                         Location end,
                                         unsigned int &unicode )
    {
        if ( end - current < 4 )
            return addError( "Bad unicode escape sequence in string: four digits expected.", token, current );

        unicode = 0;

        for ( int index = 0; index < 4; ++index )
        {
            Char c = *current++;
            unicode *= 16;

            if ( c >= '0'  &&  c <= '9' )
                unicode += c - '0';
            else if ( c >= 'a'  &&  c <= 'f' )
                unicode += c - 'a' + 10;
            else if ( c >= 'A'  &&  c <= 'F' )
                unicode += c - 'A' + 10;
            else
                return addError( "Bad unicode escape sequence in string: hexadecimal digit expected.", token, current );
        }

        return true;
    }


    bool
    Reader::addError( const std::string &message,
                      Token &token,
                      Location extra )
    {
        ErrorInfo info;
        info.token_ = token;
        info.message_ = message;
        info.extra_ = extra;
        errors_.push_back( info );
        return false;
    }


    bool
    Reader::recoverFromError( TokenType skipUntilToken )
    {
        int errorCount = int( errors_.size() );
        Token skip;

        while ( true )
        {
            if ( !readToken( skip ) )
                errors_.resize( errorCount ); // discard errors caused by recovery

            if ( skip.type_ == skipUntilToken  ||  skip.type_ == tokenEndOfStream )
                break;
        }

        errors_.resize( errorCount );
        return false;
    }


    bool
    Reader::addErrorAndRecover( const std::string &message,
                                Token &token,
                                TokenType skipUntilToken )
    {
        addError( message, token );
        return recoverFromError( skipUntilToken );
    }


    Value &
    Reader::currentValue()
    {
        return *( nodes_.top() );
    }


    Reader::Char
    Reader::getNextChar()
    {
        if ( current_ == end_ )
            return 0;

        return *current_++;
    }


    void
    Reader::getLocationLineAndColumn( Location location,
                                      int &line,
                                      int &column ) const
    {
        Location current = begin_;
        Location lastLineStart = current;
        line = 0;

        while ( current < location  &&  current != end_ )
        {
            Char c = *current++;

            if ( c == '\r' )
            {
                if ( *current == '\n' )
                    ++current;

                lastLineStart = current;
                ++line;
            }
            else if ( c == '\n' )
            {
                lastLineStart = current;
                ++line;
            }
        }

        // column & line start at 1
        column = int( location - lastLineStart ) + 1;
        ++line;
    }


    std::string
    Reader::getLocationLineAndColumn( Location location ) const
    {
        int line, column;
        getLocationLineAndColumn( location, line, column );
        char buffer[18 + 16 + 16 + 1];
        sprintf( buffer, "Line %d, Column %d", line, column );
        return buffer;
    }


    std::string
    Reader::getFormatedErrorMessages() const
    {
        std::string formattedMessage;

        for ( Errors::const_iterator itError = errors_.begin();
                itError != errors_.end();
                ++itError )
        {
            const ErrorInfo &error = *itError;
            formattedMessage += "* " + getLocationLineAndColumn( error.token_.start_ ) + "\n";
            formattedMessage += "  " + error.message_ + "\n";

            if ( error.extra_ )
                formattedMessage += "See " + getLocationLineAndColumn( error.extra_ ) + " for detail.\n";
        }

        return formattedMessage;
    }


    std::istream& operator>>( std::istream &sin, Value &root )
    {
        Json::Reader reader;
        bool ok = reader.parse( sin, root, true );

        //JSON_ASSERT( ok );
        if ( !ok ) throw std::runtime_error( reader.getFormatedErrorMessages() );

        return sin;
    }


} // namespace Json
